Law enforcement agents investigate a fatal shooting in the Seminole Heights neighborhood in Tampa, Fla., Tuesday, Nov. 14, 2017. Police searched the neighborhood after a person was shot dead, possibly by a serial killer. Spokesman Steve Hegarty said detectives can't immediately say whether the shooting is related to last month's 10-day spree where three people were slain, but officers are treating it like it is. (Jones, Octavio/Tampa Bay Times via AP)

Law enforcement agents investigate a fatal shooting in the Seminole Heights neighborhood in Tampa, Fla., Tuesday, Nov. 14, 2017. Police searched the neighborhood after a person was shot dead, possibly by a serial killer. Spokesman Steve Hegarty said detectives can't immediately say whether the shooting is related to last month's 10-day spree where three people were slain, but officers are treating it like it is. (Jones, Octavio/Tampa Bay Times via AP)

Law enforcement agents investigate a fatal shooting in the Seminole Heights neighborhood in Tampa, Fla., Tuesday, Nov. 14, 2017. Police searched the neighborhood after a person was shot dead, possibly by a serial killer. Spokesman Steve Hegarty said detectives can't immediately say whether the shooting is related to last month's 10-day spree where three people were slain, but officers are treating it like it is. (Jones, Octavio/Tampa Bay Times via AP)

TAMPA, Fla. (AP) — Police and federal agents with rifles checked car trunks, banged on doors and gathered forensic evidence in a Tampa neighborhood Tuesday as they hunted for the killer believed responsible for gunning down four people for no apparent reason in just over a month.

The normally quiet, working-class Seminole Heights section of bungalows and palm trees was sealed off with yellow crime-scene tape after the latest killing in the neighborhood — that of a 60-year-old man who was shot from behind as he crossed a street shortly after 5 a.m.

Interim Tampa Police Chief Brian Dugan said it is extremely possible that the killer — or killers — live in the neighborhood.

"Whoever is doing it, they're familiar with the neighborhood and they're able to vanish very quickly," Dugan said.

Residents and police have been on edge since Oct. 9, when 22-year-old Benjamin Mitchell was shot to death. Two days later, 32-year-old Monica Hoffa, was slain. And on Oct. 19, Anthony Naiboa, 20, was killed after taking the wrong bus home from his new job.

On Tuesday, Ronald Felton, an unemployed construction worker who volunteered at a food bank, was gunned down.

Police cars with flashing lights sat at dozens of intersections, and one major thoroughfare was entirely shut down for much of the day. Law enforcement took over the parking lot at a Baptist church, and a federal Bureau of Alcohol, Tobacco, Firearms and Explosives bus was parked at the makeshift command center. Law officers questioned people and took down cell numbers.

"This was a very decent neighborhood until the last couple of months," sighed Sherry Street, 50, a cook who has lived in the area for seven years. "Up until recently I used to accidentally fall asleep with the door unlocked."

Street said she has stopped walking to the store, taking the bus or sitting outside to smoke at night. Her friends would often stop by and hang out on her porch to talk, but "now they're like, 'I'm not coming to see you.'"

Her neighbors have also changed their routines. Gone were the Halloween decorations of years past. Gone are the dog walkers. And the young woman with the beautiful redheaded twin girls — Street hasn't seen them in weeks.

"At 7 o'clock you can come out this door and you won't hear a sound," she said.

All of October's victims were either getting on or off a city bus, or were at a bus stop, when they were shot, police said. It was unclear if Tuesday's victim was near a bus stop.

"When I first divorced and moved here, I stayed in some pretty rough areas. But I've never seen anything like this. Maybe I need to consider moving," Street said, shaking her head. "It's some crazy person. That's all you can explain it. Because why? They're just targeting innocent people and shooting them."

Police gained a better description of the suspect after the fourth killing, saying a witness described him as a black male, 6 feet to 6-foot-2, with a thin build and light complexion. He had a large black pistol and was last seen all in black.

Previously, officers didn't have much to go on other than a grainy black-and-white video of a person running near one of the crime scenes.

Bryanna Fox, a criminology professor at the University of South Florida in Tampa, said it is unusual for a serial killer to use a gun.

"A lot of serial killers prefer other methods such as knives or strangulation," she said. "Those tend to be more one-on-one, and that's what most serial killers prefer, a more intimate experience."